package pascal

import (
	"fmt"
	"reflect"
	"testing"
)

var triangleTestCases = [][]int{
	{1},
	{1, 1},
	{1, 2, 1},
	{1, 3, 3, 1},
	{1, 4, 6, 4, 1},
	{1, 5, 10, 10, 5, 1},
	{1, 6, 15, 20, 15, 6, 1},
	{1, 7, 21, 35, 35, 21, 7, 1},
	{1, 8, 28, 56, 70, 56, 28, 8, 1},
	{1, 9, 36, 84, 126, 126, 84, 36, 9, 1},
	{1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1},
	{1, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1},
	{1, 12, 66, 220, 495, 792, 924, 792, 495, 220, 66, 12, 1},
	{1, 13, 78, 286, 715, 1287, 1716, 1716, 1287, 715, 286, 78, 13, 1},
	{1, 14, 91, 364, 1001, 2002, 3003, 3432, 3003, 2002, 1001, 364, 91, 14, 1},
	{1, 15, 105, 455, 1365, 3003, 5005, 6435, 6435, 5005, 3003, 1365, 455, 105, 15, 1},
	{1, 16, 120, 560, 1820, 4368, 8008, 11440, 12870, 11440, 8008, 4368, 1820, 560, 120, 16, 1},
	{1, 17, 136, 680, 2380, 6188, 12376, 19448, 24310, 24310, 19448, 12376, 6188, 2380, 680, 136, 17, 1},
	{1, 18, 153, 816, 3060, 8568, 18564, 31824, 43758, 48620, 43758, 31824, 18564, 8568, 3060, 816, 153, 18, 1},
	{1, 19, 171, 969, 3876, 11628, 27132, 50388, 75582, 92378, 92378, 75582, 50388, 27132, 11628, 3876, 969, 171, 19, 1},
}

var testSize = len(triangleTestCases)

func TestTriangle(t *testing.T) {
	for n := 1; n <= testSize; n++ {
		t.Run(fmt.Sprintf("Triangle until row %d", n), func(t *testing.T) {
			got := Triangle(n)
			want := triangleTestCases[:n]
			if !reflect.DeepEqual(got, want) {
				help := getHelp(got, want)
				t.Fatalf("Triangle(%d)\nhelp: %s\ncomplete got:%s\ncomplete want:%s\n", n, help, format(got), format(want))
			}
		})
	}
}

func getHelp(got, want [][]int) string {
	if len(got) != len(want) {
		return fmt.Sprintf("expected %d rows, got: %d", len(want), len(got))
	}
	for i, gotLine := range got {
		if !reflect.DeepEqual(gotLine, want[i]) {
			return fmt.Sprintf("first difference in row with index: %d\n got: %v\nwant: %v", i, gotLine, want[i])
		}
	}
	return ""
}

func format(t [][]int) (s string) {
	for _, r := range t {
		s = fmt.Sprintf("%s\n%v", s, r)
	}
	return s
}

// BenchmarkPascalsTriangleFixed will generate Pascals Triangles against the
// solution using triangles of fixed size 20.
func BenchmarkPascalsTriangleFixed(b *testing.B) {
	if testing.Short() {
		b.Skip("skipping benchmark in short mode.")
	}
	for i := 0; i < b.N; i++ {
		Triangle(testSize) // same length as the test for correctness above
	}
}

// BenchmarkPascalsTriangleIncreasing will generate Pascals Triangles against the
// solution using triangles of an increasingly larger size from 1 to 20.
func BenchmarkPascalsTriangleIncreasing(b *testing.B) {
	if testing.Short() {
		b.Skip("skipping benchmark in short mode.")
	}
	for i := 0; i < b.N; i++ {
		for x := 0; x <= testSize; x++ {
			Triangle(x)
		}
	}
}
